• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 45
  • 13
  • 7
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 98
  • 22
  • 19
  • 13
  • 11
  • 10
  • 8
  • 7
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Palladium (II) and platinum (II) complexes of cyanomethyl (diphenyl) phosphine and o-cyanophenyl (diphenyl) phosphine

Trujillo, Horeb 03 June 2011 (has links)
Cyanomethyl(diphenyl)phosphine (L) and o-cyanopheryl(diphenyl)phosphine (LI) react with H2PdX4 (X = Cl, Br) or K2PtCl4 to yield complexes of the type MX2E2(M = Pd, Pt; E = L, L'). Infrared and nuclear magnetic resonance spectroscopic data indicate that L and Ĺ are coordinated through the phosphorus atom, and that the Land L'-containing complexes have cis and trans geometries, respectively, The MC12E2 complexes react with potassium thiocyanate to yield derivatives of the type 1,(NCS):,L9, in which the thiocyanate groups are nitrogen-bonded to 'the metal.The reaction of L, L' or PdX2E2 (E = L or L') with either PdX2 (X = Cl, Br) or Na2PdX4, in a 1 to 1.1 mole ratio yields complexes of the type (PdX2E.)n. Infrared data indicate that the (PdX2L)n complexes are ligand- and the (PdX2L')n complexes halogen-bridged species.Ball State UniversityMuncie, IN 47306
52

Ligand properties of some phospine-nitrile systems

Worstell, Jonathan Harlan 03 June 2011 (has links)
3-Cyanopropyl(diphenyl)phosphine was synthesized from chloro(diphenyl)phosphine and 4-chlorobutyronitrile. This new ligand, along with (C6H5)2PCH2CN and (C6H5)2PCH2CH(CH3)CN were reacted with Re(CO)5X (X=Cl,Br) in 1:1 and 1:2.5 (metal:ligand) mole ratios.For all ligands, complexes with the stoichiometry Re(CO)3L2X were isolated from the 1:2.5 mole ratio reactions. Spectroscopic data suggest that the CO groups are facial and the ligands cis to each other.For all ligands, complexes with the stoichiometry Re2(CO)6L2X2 were isolated from the 1:1 mole ratio reactions. Spectroscopic evidence suggests that all the complexes are ligand bridged dimers which utilize the phosphorus and nitrogen lone pairs of the ligand.Ball State UniversityMuncie, IN 47306
53

Proton and carbon-13 nuclear magnetic resonance studies of poly-[bicyclobutane-1-carbonitrile] and related monomers

Kao, Lung-Fa January 1980 (has links)
No description available.
54

Mécanismes d'action des composés oestrogéniques dans la neuroprotection chez la souris MPTP = Neuroprotective mechanisms of estrogenic compounds in MPTP mice /

Al-Sweidi, Sara. January 2008 (has links)
Thèse (M.Sc.)--Université Laval, 2008 . / Bibliogr.: f. 102-132. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.
55

Surface-enhanced Raman spectroscopic studies of organonitriles on copper colloids

Coyle, Candace Mikki, January 1999 (has links)
Thesis (Ph. D.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains xvii, 169 p. : ill. Vita. Includes abstract. Includes bibliographical references.
56

Surface enhanced Raman spectroscopic studies of the orientation of organonitriles on metal colloids

Ramakrishnan, Ramaa N. January 2000 (has links)
Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xi, 81 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.
57

Pesquisa cooperativa: o projeto de desenvolvimento de fibras de carbono para aplicacao em ultracentrifugas / Cooperative research: the carbon fiber development for uranium centrifuges project

QUEIROZ, PAULO C.B. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:55:41Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:07Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
58

Pesquisa cooperativa: o projeto de desenvolvimento de fibras de carbono para aplicacao em ultracentrifugas / Cooperative research: the carbon fiber development for uranium centrifuges project

QUEIROZ, PAULO C.B. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:55:41Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:07Z (GMT). No. of bitstreams: 0 / Em um cenário nacional de grandes dificuldades orçamentárias, soluções criativas que conjuguem os esforços de instituições em prol de uma finalidade comum são sempre desejáveis. Neste trabalho, analisa-se o desenvolvimento de fibras de carbono de alto desempenho para aplicação em ultracentrífugas nucleares e o projeto de Pesquisa Cooperativa que o viabilizou. A fibra de carbono com as características necessárias a empreendimentos desse tipo é um insumo de grande complexidade tecnológica. A produção é concentrada em alguns poucos produtores mundiais e seu comércio é alvo de restrições e salvaguardas internacionais. Não há produção no Brasil. É considerada material de uso dual, ou seja, pode ter tanto aplicações exclusivamente civis, como militares. A Marinha do Brasil utiliza essa fibra na fabricação de ultracentrífugas nucleares, nas quais materiais que conjuguem leveza, rigidez e resistência de alto nível são extremamente desejáveis, pois aumentam a eficiência na separação isotópica. Sua fibra de carbono, importada, é baseada na poliacrilonitrila (PAN), comercialmente mais difundida, mais barata e utilizada em aplicações similares. A necessidade de desenvolvimento nacional é decorrência de dificuldades em sua aquisição. Para tanto, foi organizada uma parceria de pesquisa entre o Centro Tecnológico da Marinha (CTMSP), a UNICAMP, a USP e a empresa RADICIFIBRAS, com apoio financeiro de uma agência governamental (FINEP), para a produção nacional de fibra de carbono baseada na PAN. A pesquisa realizada identificou as práticas de sucesso alcançadas, bem como os referenciais teóricos de Projetos de Pesquisa Cooperativa. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
59

Hidrólise enzimática de nitrilas pelo fungo de origem marinha Aspergillus sydowii CBMAI 934 / Enzymatic hydrolysis of nitriles by the fungus of marine origin Aspergillus sydowii CBMAI 934

Juliêta Rangel de Oliveira 14 December 2012 (has links)
No presente estudo, uma triagem foi realizada com 12 fungos marinhos Penicillium miczynskii CBMAI 930, Penicillium raistriicki CBMAI 931, Aspergillus sydowii CBMAI 933, Aspergillus sydowii CBMAI 934, Aspergillus sydowii CBMAI 935, Bionectria sp. CBMAI 936, Penicillium oxalicum CBMAI 1185, Penicillium citrinum CBMAI 1186, Penicillium decaturense CBMAI 1234, Penicillium raistriicki CBMAI 1235, Cladosporium sp. CBMAI 1237 e Aspergillus sydowii CBMAI 1241 para avaliar o potencial enzimático destes micro-organismos frente à fenilacetonitrila 1. Estes micro-organismos foram isolados de esponjas e alga coletadas do litoral norte do estado de São Paulo. A triagem foi realizada em meio sólido mineral suplementado com glicose e fenilacetonitrila 1 como única fonte de nitrogênio. Dentre os fungos, 8 adaptaram-se muito bem ao substrato 1 nas respectivas quantidades 5 µL (0,04 mmol), 10 µL (0,08 mmol) e 15 µL (0,12 mmol). Em seguida, a triagem foi realizada em meio líquido (20 µL (0,17 mmol), 40 µL (0,35 mmol) e 60 µL (0,50 mmol) de fenilacetonitrila 1 e obteve um bom crescimento de massa micelial dos fungos. Experimentos realizados na ausência de fenilacetonitrila 1, tanto em meio sólido, quanto em meio líquido, não promoveram o crescimento microbiano, evidenciando que as enzimas capazes de hidrolisarem nitrilas presente no sistema catalítico são construtivas. A fenilacetonitrila 1 foi biotransformada ao ácido 2-(2-hidroxifenil)acético 1b (51% pelo fungo A. sydowii CBMAI 934) por todos os fungos adaptados. Devido ao bom crescimento do fungo A. sydowii CBMAI 934 em meio mineral sólido e líquido na presença de fenilacetonitrila 1, este fungo foi selecionado para promover reações de hidrólise frente a diferentes organonitrilas, arilcetonitrilas: 4-fluorofenilacetonitrila 2, 4-clorofenilacetonitrila 3, 4-metoxifenilacetonitrila 4, 2-metilfenilacetonitrila 5, 3-metilfenilacetonitrila 6, 4-metilfenilacetonitrila 7 aos seus correspondentes ácidos carboxílicos 4-fluorofenilacético 2a (51%), 4-clorofenilacético 3a (55%), 4-metoxifenilacético 4a (43%), 2-metilfenilacético 5a (76%), 3-metilfenilacético 6a (52%) e 4-metilfenilacético 7a (46%), em nitrila alifática, 2-(1-ciclo-hexen-1-il)acetonitrila 8 ao ácido 2-(1-ciclo-hexen-1-il)acético 8a (28%) e nitrila hetero-aromática, 2-cianopiridina 19 a 2-piridinamida 19a. As reações foram acompanhadas por GC-FID e os produtos de biotransformações foram isolados e caracterizados por GC-MS, HRMS, RMN de 1H e de 13C. Este trabalho envolveu o primeiro estudo frente à biotransformação de nitrilas por micro-organismos de origem marinha. / In the present study, a screening of 12 marine fungi Penicillium miczynskii CBMAI 930, Penicillium raistriicki CBMAI 931, Aspergillus sydowii CBMAI 933, Aspergillus sydowii CBMAI 934, Aspergillus sydowii CBMAI 935, Bionectria sp. CBMAI 936, Penicillium oxalicum CBMAI 1185, Penicillium citrinum CBMAI 1186, Penicillium decaturense CBMAI 1234, Penicillium raistriicki CBMAI 1235, Cladosporium sp. CBMAI 1237 and Aspergillus sydowii CBMAI 1241 was done in order to evaluate the enzymatic potential of these microorganisms in phenylacetonitrile 1. These microorganisms were isolated from sponges and algae collected at the north shore of Sao Paulo State. The screening was carried out in solid mineral medium supplemented with glucose and phenylacetonitrile 1 as the only source of nitrogen. Among the fungi, 8 adapted to the subtract really well 5 µL (0,04 mmol), 10 µL (0,09 mmol) and 15 µL (0,13 mmol). Afterwards, a screening was carried out in liquid medium 20 µL (0,17 mmol), 40 µL (0,35 mmol) and 60 µL (0,50 mmol) of phenylacetonitrile 1) and a great mass of the fungi was obtained. The phenylacetonitrile 1 was biotransformed in the acid 2-(2-hydroxyphenyl)acetic 1b (51% by the fungus A. sydowii CBMAI 934) by all the adapted fungi. Experiments carried out without phenylacetonitrile 1, both in solid and liquid media did not show microbial growth. Enzymes which hydrolyzed nitriles present in the catalytic system were constructive. Due to the good growth rate of the fungus A. sydowii CBMAI 934 in solid and liquid mineral media in presence of phenylacetonitrile 1, this fungus was selected to promote hydrolysis reactions in different organonitriles, arylacetonitriles: 4-fluorophenylacetonitrile 2, 4-chlorophenylacetonitrile 3, 4-methoxyphenylacetonitrile 4, 2-methylphenylacetonitrile 5, 3-methylphenylacetonitrile 6, 4-methylphenylacetonitrile 7 in their corresponding carboxylic acids 4-fluorophenylacetic 2a (51%), 4-chlorophenylacetic 3a (55%), 4-methoxyphenylacetic 4a (43%), 2-methylphenylacetic 5a (76%), 3-methylphenylacetic 6a (52%) and 4-methylphenylacetic 7a (46%), aliphatic nitrile 2-(1-cyclohexen-1-yl)acetonitrile 8 to 2-(1-cyclohexen-1-yl)acetic acid 8a (28%) and heteroaromatic nitrile 2-cyanopiridine 19 to 2-pyridinecarboxamides 19a. The reactions were monitored by GC-FID and the biotransformation products were isolated and characterized by GC-MS, HRMS and 1H and 13C NMR. This work involved the first study on the biotransformation of nitriles by marine microorganisms.
60

Complexes oléfiniques de titane : synthèse asymétrique et applications / Titanium olefinic complexes : asymetric synthesis and applications

Setzer, Paul 01 June 2012 (has links)
La réaction de Kulinkovich, découverte en 1989, permet la transformation d’esters encyclopropanols par réaction avec un complexe oléfinique de titane. Cette réaction a été appliquée en 2001 à la conversion des nitriles en cyclopropylamines primaires.Nous avons tout d’abord effectué une étude de la cyclopropanation asymétrique d’un cyanoester par un complexe chiral de titane. Une méthode d’évaluation rapide de l’induction asymétrique de ligands chiraux a été mise au point, et a permis de réaliser un screening dediols chiraux. Les meilleurs résultats ont été obtenus avec le TADDOL, qui a fourni des excès énantiomériques moyens, mais notre méthode d’évaluation reste un atout pour l’évaluation d’autres types de ligands chiraux.Une méthode originale de formation de 1,4-dicétones via un complexe oléfinique de titane a été découverte puis optimisée, et ses limites ont été explorées. La préparation des 1,4-dicétones s’effectue en deux étapes à partir d’acides carboxyliques avec des rendements modestes à satisfaisants. L’utilisation de réactifs peu coûteux et peu toxiques ainsi que la grande diversité structurale accessible rendent notre méthode de synthèse compétitive vis-àvis de celles décrites dans la littérature.Plusieurs études réalisées précédemment par notre équipe ont permis de synthétiser de façon exclusive les isomères (Z) de divers 2,3-méthanoaminoacides. Nous avons développé au cours de cette thèse une voie de synthèse des isomères (E) et (Z) de la 2,3-méthanolysineprotégés de façon orthogonale, via la cyclopropanation diastéréosélective d’une cyanhydrinebenzylée. La flexibilité de cette stratégie permet d’envisager la préparation des isomères (E)et (Z) de nombreux autres analogues contraints d’acides aminés. / The Kulinkovich reaction, discovered in 1989, allows the titanium-mediatedtransformation of esters into cyclopropanols using Grignard reagents. This reaction wasextended to other substrates, notably nitriles which afford primary cyclopropylamines. First, a study of the asymmetric cyclopropanation of a cyanoester using a chiral titaniumcomplex has been carried out. A method allowing the fast assessment of the asymmetricinduction of chiral ligands has been worked out, and used to conduct a screening of chiraldiols. The best results were obtained with the original TADDOL, which furnished averageenantiomeric excesses, but our method remains an asset for the evaluation of other types ofchiral ligand.An original method for the formation of 1,4-diketones using an olefinic titanium complexhas been discovered, optimized, and explored. We established that 1,4-diketones are availablein two steps from carboxylic acids with modest to correct yields. The use of inexpensive andminimally toxic reagents as well as an access to a vast structural diversity allow our method tobe competitive beside those reported in literature.Several studies carried out previously by our team allowed the exclusive synthesis of the(Z) isomers of various 2,3-methanoaminoacids. In this present work, we developped asynthetic pathway towards (E) and (Z) isomers of orthogonaly protected 2,3-methanolysine,using the diastereoselective cyclopropanation of a benzylated cyanhydrin as key reaction. Theflexibility of this strategy allows to consider the preparation of (E) and (Z) isomers of variousother constrained aminoacid analogues.

Page generated in 0.0451 seconds